where is the maintenance port for the a/c recharge? on 1990 Audi 100

I looked online but couldn't find a simple illustration of the engine with lined labels or something similar.

2 answers 2 comments
One is on the low pressure side line the other is on the high pressure side line. Check by condensor, might be hidden by grille.
Ok, thanks ziptie12. Ill take another look.
follow the a/c lines, you should find a schrader type valve or a quick disconnect valve...
Thanks. I'll check it out again tomorrow.